Talk:Free body diagram
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I found this page rather muddled. The basic points about the free body diagram are missing:
- free body diagrams are useful for statics and dynamics, depending on whether or not the system is in equilibrium,
- a free body must never include its supports (otherwise it would not need a reaction force to maintain equilibrium),
- the force vectors on the diagram must show magnitude, direction and point of application.
Rather than getting bogged down with weight and inclined planes, it would be more useful to give clear instructions for static analysis (resolving forces and taking moments). That could lead to non-rotational dynamics, showing statics is a special case where acceleration is zero), and possibly also going on to rotational dynamics, introducing moment of inertia.
--Jack Hale 10:52, 1 May 2006 (UTC)
- I am in absolute agreement with you. A free body diagram does not contain any objects other than the one which is being acted on by certain forces. The given examples are not, in my opinion, even free body diagrams. I am editing the first paragraph to define a FBD before it describes what it is used for.--Erik the guy 06:52, 5 November 2006 (UTC)
[edit] Merge?
I think this article should be merged with section 1.2 of Classical mechanics. Jonathan48 18:28, 16 Feb 2005 (UTC)
- I considered a merge also, but then decided that maybe some example figures of free-body diagrams could go here and was going to make one or two. As-is I'd say its worthless, but I think it'd be worth keeping seperate with a figure. Laura Scudder 00:35, 6 Mar 2005 (UTC)
- I do not think a merge will be helpful. I, and several of my classmates, have found it handy to use this individual page. It would benifit from being expanded however.--Erik the guy 06:50, 5 November 2006 (UTC)
[edit] Types of Forces
I believe that this article should be editted to include
Contact forces
- Friction
- Tension
- Normal force
- Air resistance
- Applied Force
Non-Contact forces
- Gravity
- Magnetism
--Erik the guy 07:34, 5 November 2006 (UTC)
This approach is, in my opinion, a dangerous road to tread pedagogically. It makes the student think that there exists an exhaustive list of every type of vector they'll ever need, and if they memorize that list, everything will be ok. But a physics student is constantly exposed to additional forces over their tenure. Even the sticky issue that there's no such thing as a "contact force" is further complicated by the question of what a fictional force is - it doesn't seem to fit into either of those categories, but should certainly be listed on a FBD when appropriate. Rather, the student should be encouraged to think about the specific situation at hand and attempt to list all the relevant effects on the object. I've always felt it was a mistake to categorize forces at this level, the whole beauty of FBDs is that they make no distinction between forces, every force is just a vector.
What I'd like to do is change the vector section to a very general discussion of how to construct a FBD, and then move the existing material into a separate "Example" section. I'll try to do that and see how people feel.
--Hyandat 23:53, 5 November 2006 (UTC)
Yah i sort of agree with you. We cannott offer a definitive list of all possible forces. We should attempt to compose a list of some of the most common forces however, and those given above are some of the standard ones. Fictional forces can even be lister seperatly from the other two (since they are not technically forces) I just think the wiki needs a bit more info than weight and normal force.--Erik the guy 00:32, 6 November 2006 (UTC)
